Those trends didn't begin when President Trump took office. The Obama administration bailed out General Motors and Chrysler in 2009. What followed was the industry's longest period of sustained growth in decades.

Larry Summers, President Obama's top economic adviser during the bailout, said Tuesday night on Twitter that Trump didn't deserve credit.

Fiat Chrysler is not actually moving its plant. It will start making the Ram heavy-duty truck in Michigan in 2020 instead of in Saltillo, Mexico. But the company still plans to keep its Saltillo plant running, and will manufacture other vehicles there instead.